The sound of an explosion can be heard on the black box recorder of the downed Russian jet, according to reports in the French media.

The sound of an explosion could be heard on the flight data recorders, French TV station France 2 reported.

An investigator with access to the devices ruled out the possibility it was the result of an engine failure, saying the noise was not consistent.

It came after an unnamed source reportedly linked to the investigation into the black boxes claimed the Metrojet flight was ‘definitely’ blown up by an explosive device.

The claims were reported by French news magazine Le Point, which said the findings emerged after analysis of the black boxes by Russian, French, German and Irish investigators in Cairo.

The Russian President’s U-turn came after a 10-minute phone call with Mr Cameron where he suggested Britain’s decision to ban flights to and from Sharm el-Sheikh was premature.

Despite the tension between the two leaders, the Prime Minister still shared British intelligence he believes proves the disaster in Eqypt which killed 224 people on Saturday was caused by an explosion.

But Mr Cameron’s call may have worked as Russian President Vladimir Putin has now suspended all passenger flights to Egypt on the advice of his top spy.

Alexander Bortnikov, a former KGB official who is now head of the FSB security service said: ‘Until we know the real reasons for what happened, I consider it expedient to stop Russian flights to Egypt.

However, the claims by Le point also come amid reports that another source close to the investigation said the black boxes were yielding almost no useful information on establishing the cause of the disaster which claimed the lives of 224 people.

The insider said the flight data recorder ‘abruptly’ stopped working just over 20 minutes from takeoff, without giving any clue over the nature of the catastrophe which hit the plane.

And the voice recorder, including crucial conversations involving the pilots, is ‘badly damaged’ and ‘may also be useless’, according to Kommersant.

Meanwhile, it emerged that British spies were due to interrogate Egyptian baggage handlers after intercepted intelligence pointed to an ISIS mole smuggling a bomb into the hold of the doomed Russian jet.

MI5 heard ‘chatter’ from extremists in the Sinai Peninsula revealed there is a ‘high probability’ the disaster was caused by an explosion on board.

Spies also believe a ‘flash’ in the sky when the plane came down and the lack of a distress signal points to a bomb so attention is now being focussed on baggage handlers, a Downing Street source told MailOnline.

Tourists were also routinely offered the chance to avoid security altogether by paying £15 and passengers wereseen handing over cash in the long queues at Sharm today, according to the BBC.

British flights to and from Sharm el-Sheikh have been suspended because it is feared the bomb was smuggled through security or planted by airport staff – leaving 20,000 Britons stranded and 130,000 who have booked winter sun trips in limbo.

British holidaymakers stranded in the Egyptian resort face chaos after being told yesterday they can board a plane home only if they leave their bags behind – again pointing to a bomb in the hold.

Baggage handlers at the Egyptian airport with links to ISIS or other terror networks could have used their high-level security clearance to wave an explosive device through pre-flight checks.

Downing Street said it is one of a ‘range of options’ being considered as part of investigations into how a bomb could have been smuggled on board the flight.

KLM have started telling passengers leaving the Egyptian capital of Cairo that they can only take hand luggage on the plane departing.

But a Foreign Office source said Britain’s security concerns are ‘purely isolated to Sharm’, adding there is ‘no reason to suggest there are any issues in Cairo’.

Ministers believe limiting passengers to hand luggage is the best way to get them home amid fears that the airport remains vulnerable to terrorist attack.

The developments come as it was revealed Britain and Russia have joined forces to track down those responsible for blowing Flight 9268 out of the sky.

In what is already said to be the largest counter-terror operation between the two powers since the September 11 attacks, military and intelligence experts from both sides have formed a coalition in what is now an international manhunt.

Despite that, Prime Minister David Cameron still faced a furious backlash from both Russia and Egypt over his own handling of the Sharm El Sheikh crisis, as it emerged British spies uncovered intelligence that the plane crash was caused by an Islamic State bomb.

Whitehall sources revealed that, in the days after the Russian airliner was downed last weekend, they trawled back through communications data intercepted on suspects in Syria and Egypt.

This led officials at GCHQ and MI5, and US counterparts, to conclude the disaster was highly unlikely to have been an accident.

But in a tense ten-minute phone call yesterday, Vladimir Putin rounded on the Prime Minister over his declaration that the Russian Airbus was downed by a terrorist bomb.

Such a development would be a political disaster for Moscow, which would face allegations it failed to protect its own citizens.

Egypt reacted angrily to Mr Cameron’s suspension of flights to and from Sharm – a move that could deal a shattering blow to the country’s tourism industry.

Mr Putin is desperate to avoid claims the tragedy, which killed 224 people on Saturday, was a revenge attack by ISIS terrorists angered by his military intervention in Syria.

Yesterday, as Russian airlines continued to operate flights in and out of Sharm, Mr Putin criticised Mr Cameron for pre-empting the outcome of a joint inquiry by Russia and Egypt into the disaster. The Prime Minister’s official spokesman said: ‘The President underlined that he thought all countries should wait for the investigation to be completed.

‘The Prime Minister was very clear that he will be driven by what is right for the safety of British citizens and that we were right to take the action that we did based on the information that we had … and our assessment of the situation.’

The Kremlin said in a statement: ‘Vladimir Putin stressed that assessment of the causes of the crash should be based on the data that would become available in the course of the official investigation.’

Russia’s foreign ministry said it would be ‘shocking’ if Britain had suspended flights based on intelligence not shared with Moscow.

Downing Street declined to comment directly on the claim, but stressed that Mr Cameron’s national security adviser, Sir Kim Darroch, has spoken to his Russian counterpart to share details of the intelligence that lay behind the PM’s decision to ground flights.

No 10 also played down the scale of the row with Mr Putin, saying the phone call was largely ‘cordial’, with the leaders voicing a shared determination to tackle terrorism.

Egypt’s foreign minister, Sameh Shoukry, said he was very disappointed by the decision to suspend flights, accusing the UK government of making ‘a premature and unwarranted statement’ on the crash.

Foreign Secretary Philip Hammond risked further angering Egypt yesterday, suggesting there was a ‘significant possibility’ the attack was carried out by IS terrorists operating in the Sinai Peninsula, a claim Cairo dismissed as ‘propaganda’.

President Abdel Fattah El Sisi, who held talks in Downing Street yesterday, later said he was prepared to ‘co-operate’ with Britain on improving security at Sharm airport to restore confidence among the one million British tourists who visit the resort each year.

On Wednesday, a team of British aviation security experts declared the airport unsafe after identifying a series of loopholes.

Within hours, Mr Cameron had ordered the suspension of all British flights in and out of Sharm. Sources said security concerns and the intercept intelligence, left the Prime Minister with ‘no choice’ but to act.

The US has also changed its travel advice to warn against travel to Sharm, and the German national carrier Lufthansa yesterday suspended flights.

But President Sisi yesterday rejected claims security at the airport was lax. He revealed a team of British experts examined procedures at the airport and recommended changes, which were then implemented, ten months ago.

Following the review, he said the UK was satisfied procedures were adequate. The revelation that Britain gave the airport the all-clear just ten months ago will spark questions about the thoroughness of the review – and prompt speculation about whether ministers decided to go easy on Egypt at the time because of its status as an ally.

The Prime Minister’s spokesman yesterday confirmed Britain had been ‘happy’ with security at the airport after the improvements were made at the start of this year.

But she said the ‘evolving nature of the threat’ – particularly the assessment that a bomb may have been smuggled on to the Russian Airbus – had prompted a rethink.

HOW SAFE IS YOUR RESORT?

At this time of year, many of us are tempted to escape the autumn gloom, lie in the sun and gloat about those stuck at home. However, lax security and a proximity to volatile countries means many resorts may be vulnerable to attack, says GUY WALTERS.

So which countries should we be wary of visiting?

EGYPT

With 900,000 of us flying there every year, Egypt is one of the most popular tourist destinations for Britons. However, as the suspected bombing of the Russian passenger jet has shown, Egypt is far from safe. Eighty-eight people, including 11 Britons, were massacred by Islamists at Sharm el-Sheikh in 2005. Six Britons were among the 62 murdered by Islamists at Luxor at 1997.

‘We need to see what proactive security steps the Egyptians are going to take,’ says Will Geddes, the managing director of International Corporate Protection, which advises businesses and individuals on travel security and counter-terrorism. ‘However, Sharm as a resort is reasonably well protected.’

Although the Foreign Office warns that there is a ‘high threat from terrorism’, it does not advise against travel to Red Sea resorts such as Sharm and Hurghada, as well as tourist areas along the Nile, such as Luxor, Aswan, Abu Simbel and the Valley of the Kings.

MOROCCO

Although Morocco has been comparatively free of terrorism, it is feared that the country may soon become the victim of an attack in one of its popular tourist centres, such as Casablanca or Marrakesh. The Foreign Office warns that there is a ‘high threat from terrorism’, as an increasing number of Moroccans become sympathetic towards – or even join – organisations such as IS. ‘Morocco is also important for Islamists because it gives them a foothold to spring into Europe,’ says Mr Geddes. ‘However, at present there are no specific threats that I am aware of.’

In fact, along with 500,000 other Britons, Mr Geddes says that he will be visiting the country himself next year.

TUNISIA

Since the atrocity at the resort of Sousse in June, in which 30 Britons were killed, the Foreign Office has advised against all but essential travel to the country, which used to attract some one million Britons every year.

‘On balance, we do not believe the measures in place provide adequate protection for British tourists in Tunisia at the present time,’ the Foreign Office states.

‘The country has a lot of borders,’ says Mr Geddes, ‘they are mostly very weak and Tunisia simply isn’t able to provide the necessary level of security for holidaymakers.’ Nevertheless, companies such as Thomson still offer packages to resorts such as Sousse, where seven nights costs around £327 per person.

TURKEY

‘There are serious issues with Turkey at the moment,’ says Mr Geddes. ‘The Government is in a state of flux, and the borders with Syria and Iraq are permeable.’

In October, IS-backed suicide bombers killed 100 people in Ankara, although as yet there have been no attacks on tourist resorts, which are visited by 2.5million Britons a year.

The Foreign Office advises that the risk from terrorism is high, and cautions visitors to be vigilant. As Turkey is a gateway into continental Europe for the likes of IS, it is feasible resorts could be targeted. However, Turkey has a long history of dealing with terrorist organisations, and, coupled with its desire to protect revenue from tourism, it can only be hoped that its security services are doing all they can to protect their foreign visitors.

INDONESIA

When most of us think of terrorism in the Far East, our minds are cast back to 2002, when 202 people, including 27 Britons, were killed in the Bali bombings. Although there have been no comparable atrocities since, in July 2009 the JW Marriot and Ritz-Carlton hotels in Jakarta were bombed, and one Briton was killed.

The Indonesians appear to have been successful in thwarting several Islamist attacks, but as the old IRA adage goes, the terrorists only need to be lucky once. The Foreign Office says that the risk of terrorism is high, and that places such as tourist resorts are potential targets. The 250,000 of us who visit the country every year should be vigilant.

MALAYSIA

Nearly 500,000 Britons visit Malaysia every year, with many heading to islands such as Langkawi and Bunga Raya. But all is not rosy, as the Islamist Abu Sayyaf Group, based in the Philippines, has kidnapped foreigners on boat and diving trips off east Malaysia.

However, the Malaysians do seem to have met the challenge to keep their visitors safe. ‘The Malaysians have very sophisticated intelligence,’ says Mr Geddes. ‘And by and the large the resorts are safe.’ Meanwhile, the Foreign Office states that there is a ‘general threat’ from terrorism, and urges vigilance.

THAILAND

With many internal political problems, Thailand has been suffering from a great deal of violence. In August, a Briton was killed when a bomb exploded in Bangkok, while in April, a car bomb on the popular island resort of Koh Samui injured seven. As 850,000 of us visit the country every year, it is clear that any threats to Thailand should be taken seriously. The Foreign Office states there this a ‘high threat’ from terrorism, and urges vigilance.

MALDIVES

Long seen as the ultimate destination for anybody wishing for a dream holiday, the islands are nowhere near as tranquil as their idyllic beaches and waters would suggest. The president has recently declared a 30-day state of emergency after the arrest of the vice-president in connection with a supposed bomb blast on a boat. Although the Foreign Office says there is a ‘general threat’ from terrorism, it has told British tourists that resorts and airports are ‘unlikely to be significantly affected’ by the state of emergency.